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Duda Jarek
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The problem with getting quadrupole is that it requires at least two charges in a distance, while (ignoring quarks) we have only one - here it is explained by "proton bilocation", while it seems nobody considers (believes?) in quarks in nuclear physics level (? why?). I didn't say anything about electron's trajectory, |pn with electron seeing pn> can be treated e.g. with Schrodinger.
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To get quadrupole, proton in these two cases ('pn' and 'np') needs to be in a bit different places (shifted by ~fm). Electron in orbital interacts with proton e.g. through Coulomb, for which there is a tiny difference between these two cases - they are distinguishable for electron in orbital. Not true? You can says that we have superposition " |pn with electron seeing pn> - |np with electron seeing np> ", but in this case such electron doesn't see quadrupole - which seems required in deuteron-based atoms.
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Ok, let us see deuteron as "|np> - |pn>" to get quadrupole moment. Measuring proton's position, we would get pn or np ... but having electron in orbital, wouldn't it "measure" proton's position through EM interactions as there is slight difference between pn and np? Ok, we can say we have superposition:" |pn with electron seeing pn> - |np with electron seeing np> ", but would such electron see quadrupole this way? Here is some paper with deuteron based atoms, and they consider quadrupole: https://www.researchgate.net/profile/Nir_Nevo_Dinur/publication/263316174_Improved_estimates_of_the_nuclear_structure_corrections_in_mD/links/543ce7860cf2c432f7422a6b/Improved-estimates-of-the-nuclear-structure-corrections-in-mD.pdf Regarding charge shift, imagining deuteron as 6 quarks/charges - calculating e.g. Schrodinger equation for 6 charges and averaging, you would also see repulsion in statistics - shifting away charges as in quadrupole. So this is in fact question if quarks take part in nuclear binding, e.g. by some (statistical?) shifts to reduce energy. Currently for e.g. deuteron-proton or neutron scattering, there are fitted ~40 parameters models including 3-body forces ( https://en.wikipedia.org/wiki/Three-body_force ) and neglecting quark structure - we could fit anything for modelling 3 nucleons with 3-body forces. Why not try to go toward quarks to understand nuclear binding? Would we still need 3-body forces in this case?
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Exactly - this dynamical approach to explain qudrupole moment in 'pn' with angular momentum is quite controversial if thinking about it. So the question is: why not consider static instead? Seeing deuteron as (among others) 6 quarks, e.g. minimization of Coulomb energy says positive (fractional) charges should have tendency to shift far apart - as in quadrupole. Can we distinct experimentally these two possibilities: angular momentum explanation from e.g. quark-level shift of charge from proton to neutron?
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The current explanation of this quadrupole moment using angular momentum is that single proton is simultaneously on both sides of neutron: This probability cloud means that if being able to measure position of proton, we should get 1/2 - 1/2 statistics. Doesn't it mean that there is some 'pn' - 'np' oscillation?
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From https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html , third vaccine has entered phase III:
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https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html Phase III: 2 Phase II: 8 e.g. Moderna to start Phase III in July, Phase I: 10 Preclinical: 125+
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Naively we have proton-neutron with only proton charged - shouldn't it have electric multipoles as proton: zero electric dipole and quadruple moment? Quadrupole moment grows with square of distance, to get 0.2859 e fm^2 for deuteron, e.g. spitting its charge into 1/2 - 1/2 e they would need to be in ~0.76 fm distance. How could we get such charge distance for 'pn'? Thinking about it as 6 quarks it seems more doable (?) ps. However, I have seen some papers claiming nontrivial structure of charge in neutron (?): positive core, negative shell, e.g. https://inspirehep.net/literature/1377841 http://www.actaphys.uj.edu.pl/fulltext?series=Reg&vol=30&page=119 http://www.phys.utk.edu/neutron-summer-school/lectures/greene.pdf
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Deuteron is p-n, so naively should have zero electric quadrupole moment. However, experimentally it turns out quite large: 0.2859 e⋅fm2 from https://en.wikipedia.org/wiki/Deuterium#Magnetic_and_electric_multipoles This Wikipedia article explains it by adding l=2 angular momentum states - should we imagine it as a hidden dynamics? Maybe as oscillations between 'pn' and 'np' by some pi+ exchange? (but shouldn't it make it a linear antenna producing EM waves?) To describe e.g. deuteron-proton scatterings they neglect quark structure, but require three-body force ( https://en.wikipedia.org/wiki/Three-body_force) - would including quarks into considerations allow to focus only on two-body forces? But what happens with quarks when biding proton and neutron into deuteron? I am working on soliton particle model suggesting that there is a shift of charge from proton to neutron for binding of deuteron, like uud-udd slightly shifting quark u toward right, d toward left - is such explanation of quadrupole moment allowed (e.g. by QCD)?
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How quantum is wave-particle duality of Couder's walking droplets?
Duda Jarek replied to Duda Jarek's topic in Physics
This is analogy to Madelung substitution: psi = sqrt(rho) exp(iS/hbar) to Schrodinger, getting continuity equation for density rho and Hamilton-Jacobi for actions S with additional "quantum potential" corresponding to interaction with pilot wave: https://en.wikipedia.org/wiki/Pilot_wave_theory#Mathematical_formulation_for_a_single_particle -
How quantum is wave-particle duality of Couder's walking droplets?
Duda Jarek replied to Duda Jarek's topic in Physics
The complementary principle says we can observe only one of these natures at a time - is restriction for measurement like Heisenberg. So particles have at least one of these two natures at a time, the question is if objectively they cannot have both, like observed in experiments I have linked. Or like for the walking droplets with both natures at a time: http://dualwalkers.com/statistical.html -
How quantum is wave-particle duality of Couder's walking droplets?
Duda Jarek replied to Duda Jarek's topic in Physics
Most are pre-2015, more recent is e.g. anti-ferromagnet: https://math.mit.edu/~dunkel/Papers/2018SaEtAl_PRF.pdf But generally there more than 100 papers since 2016: https://scholar.google.com/scholar?as_ylo=2016&hl=en&as_sdt=0,5&sciodt=0,5&cites=13323743438210565407&scipsc= A week ago there was John Bush lecture and talked about some experiments, it should be available soon. Please elaborate - particle can have objectively both wave and corpuscular natures, or only one at a time ... what is the third option? For using both natures at a time, there is e.g. this Afshar experiment: https://en.wikipedia.org/wiki/Afshar_experiment dBB uses both natures at a time, here is its probably most known experimental confirmation: http://science.sciencemag.org/content/332/6034/1170.full More recent paper observing both natures at a time: https://www.nature.com/articles/ncomms7407 What arguments against are there? -
How quantum is wave-particle duality of Couder's walking droplets?
Duda Jarek replied to Duda Jarek's topic in Physics
Lecture about these experiments by Yves Couder: https://www.youtube.com/watch?v=QvHREXA3cl0 By John Bush: https://www.youtube.com/watch?v=8MsMuQa80fI Materials and great videos: http://dualwalkers.com/ More materials about hydrodynamical QM analogues: https://www.dropbox.com/s/kxvvhj0cnl1iqxr/Couder.pdf -
Is there a problem with this https://en.wikipedia.org/wiki/Molecular_clamp - that proteins in virus have higher energy required for fusion? Just putting mRNA into a cell, shouldn't it produce the lowest energy protein? If so, are these two configurations essentially different from anti-body perspective? Would such immune system attack infected cells and/or virus itself?
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https://news.sky.com/story/coronavirus-covid-19-vaccine-for-30-million-by-september-if-trial-succeeds-says-sharma-11990039
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https://arstechnica.com/science/2020/05/the-ars-covid-19-vaccine-primer-100-plus-in-the-works-8-in-clinical-trials/
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I see, there are many reasons China will probably be first - from 23th March: https://www.clinicaltrialsarena.com/news/china-covid-19-vaccine-trial-begins/ https://en.wikipedia.org/wiki/COVID-19_vaccine
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Good discussion about covid19 vaccine development: https://www.ted.com/talks/seth_berkley_the_quest_for_the_coronavirus_vaccine A radical approach to speedup: "Should scientists infect healthy people with the coronavirus to test vaccines?": https://www.nature.com/articles/d41586-020-00927-3
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It is hard to tell how to interpret it, but the life cost (also economical) is just too high to allow for 18 month trials to satisfy regulations - "casualties of waiting" should be included in calculations. If being at least a bit promising and excluding toxicity, I believe massive usage will start - to test it in the field in endangered regions.
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https://www.jpost.com/HEALTH-SCIENCE/Israeli-scientists-In-three-weeks-we-will-have-coronavirus-vaccine-619101
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Time crystals first described by Frank Wilczek in 2012 have got a lot of attention, recent popular review: https://physicsworld.com/a/time-crystals-enter-the-real-world-of-condensed-matter/ If I properly understand, they would like a lowest energy state spontaneously self-organizing into a periodic process - and propose sophisticated e.g. solid state experiments, or ping-pong of Bose-Einstein condensate, which don't really seem to satisfy this defining requirement (?) But Louis De Broglie has already postulated in 1924 that with electron's mass there comes some ≈10^21 Hz intrinsic oscillation: E = mc^2 = hf = hbar ω, obtained if using E=mc^2 rest mass energy in stationary solution of Schrödinger's equation: ψ=ψ0 exp(iEt / hbar). Similar oscillations come out of solution of Dirac equation - called Zitterbewegung ("trembling motion"). Here is one of its experimental confirmation papers - by observing increased absorption when ticks of such clock agree with spatial lattice of silicon crystal target: https://link.springer.com/article/10.1007/s10701-008-9225-1 Electron can be created together with positron from just 2 x 511keV energy of EM field - after which it (the field?) should self-organize into these ≈10^21 Hz intrinsic oscillations. So can we call electron an example of time crystal? What other examples of lowest energy state self-organizing into periodic process are there? ps. Beside self-organization of the lowest energy state into periodic motion (I don't see they got? in contrast to electron), they alternatively want "period doubling": that system oscillating with T period, self-organizes into 2T period process - breaking discrete time symmetry (invariance to shift by T). So these popular Couders' walkers recreating many quantum phenomena in classical systems (slides with links) also have period-doubling (can they be classified as time crystals?) - here is such plot from this paper, horizontal axis is time, lower periodic process is for liquid surface - externally enforced by some shaker, upper periodic process shows droplet trajectory - self organizing into twice larger period than enforced: But generally it seems very valuable to find analogies between spatial and temporal phenomena like crystals here. Great tool for that is Ising model: Boltzmann ensemble among spatial sequences, what mathematically is very similar to Feynman path (temporal) ensemble of QM - using this mathematical similarity, for Ising model we get Born rule, Bell violation, or analogues of quantum computers. What other phenomena can be translated between spatial and temporal dimensions?
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Imperial Collage predictions for UK - to save lives with vaccine, it would be needed by November: https://www.imperial.ac.uk/news/196234/covid19-imperial-researchers-model-likely-impact/